1. Field of the Invention
The present invention relates to a magnetic resistance device and a method of manufacturing the same. More particularly, the present invention relates to a magnetic resistance device, and a method of manufacturing the same, having a free layer or a pinned layer including an intermetallic compound or an intermetallic alloy.
2. Description of the Related Art
Due to the rapid development of super thin film deposition in a high-vacuum state, it is now possible to grow and manufacture a magnetic thin film having a thickness of only a few nanometers, which is on the order of a range of spin-spin interaction. Accordingly, many phenomena that are not observed in bulk magnetic materials have been observed, and are on the verge of being utilized, in various technology, e.g., electrical household appliances and industrial parts, such as magnetic recording heads for recording information on a super high-density information storage medium or a magnetic random access memory (MRAM).
In a magnetic resistance device, electrical resistance varies according to magnetic energy. In the case of a magnetic resistance head, which detects information recorded on an information storage medium, e.g., a hard disk drive (HDD), a giant magnetic resistance (GMR) head and a tunnel magnetic resistance (TMR) head are widely used.
A GMR structure is generally formed of a sequential stack of a ferromagnetic body, i.e., a pinned layer/a metallic nonmagnetic body, i.e., a spacer layer/a ferromagnetic body, i.e., a free layer. This structure utilizes a principle that when an electron passes through the ferromagnetic layers, a resistance value varies according to a spin arrangement of the two magnetic layers. This phenomenon can be explained by spin-dependent scattering.
A TMR structure is generally formed of a sequential stack of a ferromagnetic body/an insulating layer, i.e., a tunnel barrier layer/a ferromagnetic body. In this structure, the insulating layer is interposed between two ferromagnetic bodies so that a tunneling current varies according to the relative magnetic directions of the ferromagnetic bodies. In the case of an MRAM using the GMR phenomenon, a voltage difference is not great because the variation in resistance according to magnetic direction is relatively small.
FIG. 1 illustrates a cross-sectional view of a conventional TMR device 10. In the conventional TMR device 10, an anti-ferromagnetic layer 12 that fixes electron spin of a first ferromagnetic layer 13 is formed on a substrate 11. The first ferromagnetic layer 13, which is a pinned layer, a tunnel barrier layer 14, and a second ferromagnetic layer 15, which is a free layer, are sequentially formed on the anti-ferromagnetic layer 12. The conventional TMR device 10 uses a principle that a tunneling current varies according to the relative magnetic direction of the ferromagnetic layers 13, 15. Here, the anti-ferromagnetic layer 12 (pinning layer) that fixes the spin direction of the first ferromagnetic layer 13 (pinned layer) is formed of an anti-ferromagnetic material.
If a current is applied when the magnetic spin direction of the first ferromagnetic layer 13 (pinned layer) is opposite to the magnetic spin direction of the second ferromagnetic layer 15 (free layer), only a small amount of current flows through a barrier layer due to the high magnetic resistance of the TMR device. Conversely, when the magnetic spin direction of the first ferromagnetic layer 13 (pinned layer) is the same as that of the second ferromagnetic layer 15 (free layer), a larger current flows because the magnetic resistance is low. A magnetoresistive (MR) ratio may be expressed by Formula 1:
                              MRratio          =                                                    highMR                -                lowMR                            lowMR                        =                                          2                ⁢                                  P                  1                                ⁢                                  P                  2                                                            1                -                                                      P                    1                                    ⁢                                      P                    2                                                                                      ,                            (        1        )            where P1 represents a spin polarization of the pinned layer 13 and P2 represents a spin polarization of the free layer 15. When the MR ratio is high, a high-performance magnetic resistance device can be realized because the spins of the pinned layer 13 and of the free layer 15 are clearly distinguished.
As described above, a high MR ratio is very important for improving performance of a magnetic resistance device. In conventional magnetic resistance devices, CoFe or NiFe is used as a magnetic material for ferromagnetic layers, i.e., the free layer and the pinned layer. However, in order to manufacture more highly integrated and higher performance devices, a magnetic resistance material having a higher MR ratio is required.